The present invention relates to a flameproof resin composition comprising polysulfone (polyarylenepolyether polysulfone) and polyphosphonate.
The polysulfones have high heat resistance and excellent mechanical properties and electrical properties. Accordingly, they have been used for various construction materials as the engineering plastics. The polysulfones are self-extinguish resins. However, high flameproof property has been required for the polysulfone used as electrical parts from the viewpoints of safety.
In order to improve flameproof property of polysulfones, it has been known to produce the chlorine-containing polysulfones by adding hexachlorobenzene and tetrachlorobenzene (Bel. P. No. 737,530) or tetrachlorobiphenyl ether (G.P. No. 1,919,677) as a comonomer in the preparation of polysulfones.
In said cases, the polymerization volocity has been decreased or the average molecular weight of the product has been decreased, disadvantageously.
It has been known that an aromatic bromo compound such as hexabromobenzene or decabromobiphenyl and antimony trioxide are added to the polysulfone to impart flameproof property.
In said case, the mechanical properties have been decreased by adding relatively small amount of the aromatic bromo compound and antimony trioxide. The aromatic bromo compound is vaporized in the molding work to cause an air pollution of work environment.
It is hard to add haloalkyl phosphates because haloalkyl phosphates have low heat resistance to cause a decomposition of polysulfones in the molding operation.